Process of producing metal images by amplification of diffusion transfer images

ABSTRACT

A PROCESS FOR PRODUCING METAL IMAGES COMPRISING IMAGE-EXPOSING, THROUGH AN ORIGINAL IMAGE, A PHOTOSENSITIVE ELEMENT WHICH COMPRISES A PHOTOSENSITIVE SILVER HALIDE PHOTOGRAPHIC EMULSION LAID ON A HYDROPHILIC SURFACE OF A PLASTIC WHICH HAS A SURFACE CONTAINING A DIFFUSION TRANSFER NUCLEUS MATERIAL FORMING REVERSAL SILVER IMAGES OF THE ORIGINAL ON THE SURFACE BY A DIFFUSION TRANSFER DEVELOPIING PROCESS AND INTENSIFYING SAID SILVER IMAGES BY ELECTROLESSLY PLATING A METAL THEREON.

July 2, 1974 MAsAYosl-n 'rsusox ETAL 3,822,27

PROCESS OF PRODUCING METAL IMAGES BY AHPLIFICATION 0F DIFFUSION TRANSFER IMAGES Fned nec. 29, 1971 FIG. 2

United States Patent O U.S. Cl. 96-29 R 13 Claims ABSTRACT OF THE DISCLOSURE A process for producing metal images comprising image-exposing, through an original image, a photosensiytive element which comprises a photosensitive silver halide photographic emulsion laid on a hydrophilic surface of a plastic which has a surface containing a diffusion transfer nucleus material forming reversal silver images of the original on the surface by a dilfusion transfer developing process and intensifying said silver images by electrolessly plating a metal thereon.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a process for producing a photographic image forming base plate and, in more detail, to a process for producing metal images which comprises carrying out electroless plating corresponding to silver images formed on a plastic surface.

Description of the Prior Art In U.S. Pat. 3,033,765, Japanese Pat. Pub. No. Sho 45-25234 and British Pat. 1,183,907, processes for producing electrically conductive silver images on a surface of a silver halide photographic emulsion are described. However, in these processes, specilic chemicals are required, e.g., a hydrophilic organic colloid layer which easily absorbs moisture from the air, is exposed to the air by which it becomes soft and sticky. The electrically conductive silver images are produced on the hydrophilic organic colloid layer, which is a material such as gelatin or polyvinyl alcohol, and consequently the images are difficult to handle, and are easily injured. Furthermore, the electrical resistivity of such electrically conductive surface images is higher than that of conventional printed circuits and printing base plates.

SUMMARY OF THE INVENTION According to the process of producing metal images of the present invention, the faults shown in the prior art can be removed so that it becomes possible to produce electrically conductive metal images having a lower electric resistivity and thermally conductive images having a good thermal conductivity.

Such metal images can be produced by a process which comprises exposing a photographic image-forming base plate prepared by applying a photosensitivesilver halide photographic emulsion onto a hydrophilic surface of a plastic rlilm which contains a nucleus substance for a diffusion transfer process, producing reversal silver images of the original on said hydrophilic surface part by the diffusion transfer process, removing the silver halide photographic emulsion layer, and intensifying the reversal silver images by electroless plating.

The present inventors have thus found that the electroless plating can be carried out on silver images photographically produced on a hydrophilic part of a plastic having a hydrophilic surface part. Furthermore, they have 3,822,127 Patented July 2, 1974 ICC found that such silver images can be produced on plastics having an oleophilic surface whereafter electroless plating can be practiced on said silver images.

One object of the present invention is to provide a process producing metal images by producing silver images photographically on a surface of a plastic, and thereafter practicing the electroless plating on said silver images (hereinafter, to plate the silver images with metal by electroless plating is called intensiication).

Another object of the present invention is to produce electrically conductive surface images by intensifying the silver images produced on the surface of a plastic.

A further object of the present invention is to produce metal images having a good thermal conductivity by intensifying the silver images produced on the surface of a plastic.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a sectional view of a photographic imageforming base plate used in the present invention;

FIG. 2 shows a state of exposing this base plate;

FIG. 3 shows a photographic image forming base plate after treating with a diffusion transfer developer; and

lFIG. 4 shows a photographic image forming base plate after electroless plating treatment.

DETAILED DESCRIPTION OF THE INVENTION Regarding the degree of the hydrophilicity, any plastic is applicable provided that a diffusion transfer developing solution is permeable to silver halide photographic emulsion and that alkali solution is chemically permeable.

The degree of the hydrophilicity at the hydrophilic surface of the plastic lm or the plastic laminating layer can be indicated by, for example, a static contact angle toward the distilled water.

The following data is obtained by determining the static contact angle of the liquid drop of the distilled water fallen on a film at 25 C. in one minute using a microscope.

TABLE Static contact angle, Film surface degrees 1 Cellulose triacetate (TAC) film (125g) 55 TAC the surface of which was processed 22 with 10% sodium hydroxide solution at 70 C. for one minute, washed with Water and dried. 3--... Cellulose diacetate (DAC) film 59 4. DAC iihn, the surface of which was processed with 35 5%,sodiun1 hydroxide (water/methanoi=1:l) solution at 25 C. for one minute, Washed with water and dried. 5- DAC film, the surface of which was treated in the 22 same manner as in 4 but for two minutes. 6- Polyethylene terephthalate (PET) film (100g) 70 7. PET film passed through a propane gas-oxygen 48 ame at a rate of :1L/min. 8-.-.- Polyethylene (PE) film 93 9- PE hlm treated with corona discharge at 70 W. using 55 n electrode having 30 cm. in width at a distance of mm. 10. TAC film processed with coating and hardening. 27 11. Polystyrene (PS) lm 82 12- PS lm treated with corona discharge at a rate of 200 15 Besides polyvinyl alcohol, the hydrophilic lm includes partially saponitied polyvinyl alcohol hn, partially saponilied hydroxyethyl polyvinyl alcohol film, cellophane, polyethylene laminated cellophane, anti-humidity cellophane, polyethylene oxide films, methyl cellulose lms and gelatin film.

If the entire film is not hydrophilic such as TAC, the hydrophilic portion must be thick more than 0.05, preferably more than 0.1;, which was confirmed by an electron microscope.

In the present specification, the term hydrophilic surface part includes the following three cases.

(1) Plastic films wherein only the surface is treated to render the same hydrophilic, e.g., with a chemical agent, by corona discharge processing or by flame treatment.

Example (1a) A cellulose organic acid ester sheet which is originally oleophilic (cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate and cellulose acetate butyrate) is contacted with an aqueous solution of an alkali, a mixture of alkali containing water or a solvent or an alkali containing solvent. There will result a cellulose organic acid ester sheet only the surface of which becomes hydrophilic. In this case, the degree of hydrophilic property in the thickness direction of the sheet is not uniform, but lowers continuously from the surface to the interior of the sheet.

Example l-b) Polyethylene terephthalate film is treated by flame treatment to give the same decreasing hydrophilic property.

Example (l-c) A polyethylene film is treated by corona discharging to give the same decreasing hydrophilic property.

(2) Oleophilic plastic films to a surface of which a hydrophilic binder is applied.

Example (2-a) A cellulose triacetate film to which gelatin or polyvinyl alcohol is applied.

Example (2-b) A polyester film to which a vinyl chloride-vinyl acetate copolymer is initially applied and casein thereafter applied.

(3) Hydrophilic plastic films. For example, a polyvinyl alcohol film.

These hydrophilic surface parts are made to contain diffusion transfer nuclei. Examples of diffusion transfer nuclei are, for example, colloidal heavy metals such as colloidal silver, sulfur compounds such as silver sulfide, nickel sulfide, cadmium sulfide and zinc sulfide and selenium compounds such as silver selenide and nickel selenide, which are known substances commonly used in diffusion transfer processes. The diffusion transfer nuclei may be introduced after production of the hydrophilic surface or may be added at the film forming process before carrying out the hydrophilic treatment. Further, the diffusion transfer nuclei may be introduced into the hydrophilic surface part after application of a hydrophilic |binder such as gelatin, gelatin derivatives, polyvinyl alcohol, casein, carboxymethyl cellulose and alginic acid, or the above-mentioned hydrophilic binder to which the diffusion transfer nuclei are added may be applied onto a surface of the oleophilic plastic films. The minimum thickness of the hydrophilic layer containing diffusion transfer nucleus material is equal to the thickness of the hydrophilic layer or less than the thickness of the hydrophilic layer. The thickness of the hydrophilic layer is more than 0.25/2, preferably more than 0.4p., it is confirmed by an electron microscope.

One embodiment of the present invention will now be explained referring to the drawings.

FIG. 1 shows a sectional view of a photographic image forming base plate used in the present invention, in which an oleophilic plastic sheet (for example, a cellulose organic acid ester sheet) 1 has a hydrophilic surface part 4 containing diffusion transfer nuclei 2 and a photosensitive silver halide photographic emulsion layer 3 applied thereto.

FIG. 2 shows the exposed state of the photographic image forming base plate of FIG. 1 which has been exposed to light through an original. In the emulsion layer 3, 3A represents an exposed part, that is a part corresponding to a non-image part of the original, and 3B represents a non-exposed part, that is, a part corresponding to an image part of the original. As the original, line drawings or half-tone images may be used. Exposure may be carried out directly from a continuous gradation original using a screen. Exposure may be practiced by contact printing or enlarging.

The exposed photographic image forming base plate is then treated by a diffusion transfer development. The developer which is used in the common diffusion transfer process contains a silver halide solvent together with a developing agent. Representative silver halide solvents are, for example, thiosulfate compounds, thiocyanate compounds, and sodium sulfite.

FIG. 3 shows the photographic image forming base plate after treating with the diffusion transfer developer, in which silver images are formed on exposed parts 3A of the emulsion layer. These images are negative to the original. On the other hand, silver images 1B are formed on the hydrophilic surface part 4 underneath unexposed parts 3B of the emulsion layer. These images are positive to the original, and are produced by diffusion of the complex salt of silver halide from the non-exposed parts 3B to the hydrophilic surface part 4 containing the diffusion transfer nuclei material 2 by silver halide solvent included in the developer, by which the complex salt is reduced at the site of the nuclei material 2 by the developing agent to produce metallic silver 1B. The developed photographic image base plate is treated with warm water to remove the emulsion layer 3. Complex salt of silver halide means silver complex compound, that is, soluble silver complex salt, for example, Ag(S2O3)-, Ag(S2O3)23-, Ag (S203 )a5-a Ag (SCN 2, etc- FIG. 4 shows the state of the photographic image forming base plate after plating following removal of the emulsion layer 3. By the electroless plating, metal silver images 1B formed in the hydrophilic surface 4 are intensified by metal images 5.

As the organic colloid for the silver halide emulsion layer used in the present invention, gelatin or other natural or synthetic colloidal binders may 'be used. The binder having a generic criteria is alkali permeable binder, hydrophilic binder or gelatin compatible binder. Such binders include water-permeable or water-soluble polyvinyl alcohol and derivatives thereof, for example, partially saponified polyvinyl acetate [the one part of polyvinyl alcohol is saponified, and the other parts of polyvinyl alcohol are formed hydroxyl group. See the following.

Polyvinyl ether and acetals which contain many grafted groups -CH2CHOH- [graft-copolyymerized to many functional groups in polymer chain] and interpolymers of vinyl acetate and an addition-polymerizable unsaturated compounds such as maleic anhydride, ethyl acrylate, ethyl methacrylate and styrene. The colloids lastly described type are disclosed in U.S. Pats. 2,276,322, 2,276,323 and 2,347,811. Preferred polyvinyl acetals include polyvinyl acetaldehyde acetal, polyvinyl butyraldehyde acetal and polyvinyl sodium o-sulfobenzaldehyde acetal. Other useful colloidal binders include poly-n-vinyl lactams as described in U.S. Pat. 2,495,918, copolymers of N-acrylamide alkylbetaine as described in U.S. Pat. 2,833,050, cellulose ethers and esters, colloidal albumin, zein and polyacrylamide.

Similarly, the silver halide emulsions can contain silver chloride, silver bromide, silver iodide or mixtures thereof, and can be selected from the known emulsions containing optical sensitizers, chemical sensitizers, antifogging compounds, emulsion hardening agents, plasticizing compounds, wetting agents, toning agents and frosting agents.

In order to enhance resolving power and prevent halation, an antihalation layer can be applied to the back of the support.

The metal images produced as above may be electrically conductive surface images and thermally conductive surface images. The conductivity of the metal images is less than `6 'K2/square, preferably less than 2 Q/square.

The difference is preferably 100 times between the con-` ductivity of the metal images and that of the backgrounds (non-image parts).

The silver images formed as shown in FIG. 3 are sometimes electrically conductive, but the electrical conductivity thereof is inferior to that of metal images produced by intensification, and the surface of the silver is easily injured. On the contrary, the conductivity of the metal images produced by intensification can be controlled by conditions of the electroless plating treatment and the metal images are dicult to injure. The plating thickness is important criterion, and is controlled by composition of the electroless plating bath, pH and temperature of bath. That composition contains an amount of the metal salt, a kind of the reducing agent and -an amount of the reducing agent, pH control-agent, complexing agent, reaction accelerator, etc.

The term electroless plating is also called chemical plating, and any metal such as nickel, copper, chromium, cobalt and tin may be used for intensifying the silver images of the invention. Silver images produced by the prior art as described in,U.S. Pat. 3,033,765, Jap. Pat. Pub. No. Sho 45-25234 and British Pat. 1,183,907, or silver images formed on a multi-layer lm as described in Jap. Pat. P-ub. No. Sho 45-29876 have the faults that it is diicult to intensify with metal images by electroless plating, that the backg-round is soiled at intensification and intensiiication is weak.

As electroless plating procedures, common methods are described in Boshyokumekki to Kagakumekki written by Boshin Ro, published by Daily Industry Newspaper Otiice (1961) and Electroless Copper Plating, American Electroplaters Society, Vol. 46, pages 264- 276 (1959) written by E. B. Saubestre can be used. A

lcommon process of electroless plating will now be described. After a sheet having metal silver images as shown in IFIG. 3 is activated by dipping in an aqueous formalin solution and then in an aqueous solution of a noble metal compound (e.g., 2% palladium chloride; pH 2.0), the sheet is dipped in a copper electroless plating solution, by which the silver images are plated with metal copper. In this process, though the treatment of dipping in the aqueous formalin solution is not always required, it is possible to make rather sharp metal images by this treatment. In the case where the metal silver images formed in FIG. 3 are connected continuously, it is possible to carry out electrolytic plating instead of electroless plating.

'Ihe following process may be employed when the silver metal image is electroless plated.

( l) sensitizing by solution of Sn2+ or Ti3+;

(2) activating by solution of metal salt, said metal Salt is palladium (II) chloride [PdCl2], hydrogen gold (IV) chloride [HAuCl4], diaminesilver nitrate [As(NH3)2N0-31, ete;

(3) plating bath by copper electroplating, nickel electroplating, silver electroplating, gold electroplating, etc.

The present invention may not require sensitizing and hardly requires activating. The activating will result in easy plating on the silver metal.

In the present invention, plating bath includes electroless plating bath of plastics, preferably electroless plating bath of low temperature type, and said temperature is less than the softening point of plastics.

Examples of the said electroless plating bath are as follows.

6 A. NICKEL PLATING BATH I. Nickel electroless plating bath (1) A. Brenners bath:

Nickel sulfate ..-g/l-- 40 Sodium citrate g./l 24 Sodium acetate g./1 14 Sodium hypophosphite ..g./l.. 20 Ammonium chloride g./1 5 pH 5.5 Temperature C 40 to 60 (2) H. Narcuss bath:

Nickel sulfate g./l-.. 35 Sodium citrate g./l 10 Sodium acetate g./l 10 Sodium hypophosphite g./l 15 Magnesium sulfate g./l 20 Duponol C 1% solution ml 10 (3) L. Dominikovs bath:

Nickel sulfate g./l 20 Sodium citrate g./l 45 Sodium hypophosphite g./l 20 Ammonium chloride g./l.. 30 Ammonia Water ml 50 to 55 (4) K. Langs bath:

Nickel sulfate g./l 30 Sodium citrate g./l 10 Sodium succinate g./1 20 Sodium acetate g./l 20 Diethylaminoborazane ml 3 Methanol ml 50 Stabilizer g ll..- 0.01

II. Nickel electroless plating bath containing boron hydroxide compound (l) USP 2,942,990:

Nickel sulfate ..-g./l 20 Potassium sodium tartrate gJl-- 40 Sodium boron hydroxide ..-g/l..- 2.3 pH (by NaOH) 12.5 Temperature C,... 40 to 50 (2) `-USP 2,999,296:

Nickel sulfate g./l 50 Lactic acid g /1 25 Sodium citrate g./l 25 N-dimethylborazane g./l 2.5 Wetting agent (bubble-less) g./l 0.1 Thioglycol acid ..g./l 1.5 pH (by NH4OH) 7.0

(3) K. Langs bath:

Nickel sulfate g./l 30 Ethylenediamine g./l 60 Sodium hydroxide g./l 40 Sodium boron hydroxide g./l 0.6 stabilizer (1) pH Temperature C-- 90 to 95 1 A small amount.

(4) Langs bath:

Nickel sulfate (or nickel chloride) g./l 30 Sodium citrate g./l 10 Sodium succinate g./1. 20 Sodium acetate -..g./l 20 Diethylborazane ml 3 Methanol ml 50 Stabilizer g /l 0.01 PH 6 to 7 Temperature C-- 65 7 8 III. Nickel electroless plating bath containing (4) Aokis bath: (I) USP 2 430 581 hydrazme P t Nickel sulfate moi/1 0.1

i ar s l. 1. Nickel formate 1% solutlon) 10 Ethylene dlamtllne v mol o Hydrazine hydrate (85% solution) 1 Sodlum hypop osphlte "mo 0'1 Sodium hypophosphite (saturated solution) l 5 pH 6 to 7 Benzyltrimethyl ammonium hydroxide (42% solution) 1 V. Alkali nickel electroless plating bath Caustic-alkali plating Ammoniacal-alkali plating bath bath (1) (all.) (2) (iz-l1.) (3) (2./1.) (4) (mOL/l.) (5) (R101-fl) Composition:

Nicke1 chloride 3o 45 30 0.1 0 1 Sodium hypophosphite 11 10 0. 2 0 2 Sodium citrate 100 1 c5 0. 2 0. 2 Ammonium chloride 50 50 50 Boric acid or borax- 2 0. 1 6 0. 5

pH. 8-10 8. 5-9. 5 8-9 8-9 s9 Temperature C.) 90 90-100 90 90 90 Plating rate (min/hr.) 0.3 0. 6 o. 2 0. 4o. 5

IV. Low temperature nickel electroless plating bath (hypophosphite type) (l) USP 2,940,018:

Nickel hypophosphite g./1 26.7 Boric acid ..g./l 12 Ammonium sulfate g./l 2.6 Sodium acetate g./1 4.9 pH 5.5 to 6.0 Temperature C-- 21 Plating rate mill/hr 0.04

(2) M. Schwartzs bath:

Nickel sulfate g./1.. Sodium pyrophosphate g./l 50 Sodium hypophosphite ..-g./l 25 Ammonia Water pH 10 to 11 Temperature C..- 65 to 75 Plating rate -..mill/hr-.. 0.6

(3) E. B. Sanbestres bath:

Nickel sulfate ..-moL/ 1.... 0.005 to 0.2 Sodium hypophosphite mol./1 0.01 to 0.4 Fluoride mol./l 0.2 to 1.0 Alkylamine or alkanolamine (1) Carboxylic acid salt (2) PH 7 to 11 1 One to 10 times of nickel. 2 One to 10 times of hypophosphite.

B. COPPER PLATING BATH: COPPER ELECTROLESS PLATING BATH A solution: G./l.

Copper sulfate 35 Caustic soda 49 Potassium sodium tartrate B solution--formalin 37% solution.

Dipping at 3 to l5 min. at normal temperature in mixture of the solution of A and B solution, said mixture ratio of A/B is 5/ 1.

(2) A solution:

Copper sulfate ....g./l 14 Nickel chloride g./l 4 Pormalin 37% solution mL/l-- 53 B solution:

Potassium sodium tartrate g./l 45.5 Caustic soda g./1.... 9.0 Sodium carbonate ..-g/l-- 4.2

Dipping at normal temperature in mixture of A and B solution, said 4mixture ratio of the solution A/B is l/3.

(6) Canin an (7) Sua- (8) Sau- Name Cahills McCornell's bestres (1) bestres (2) (9) Godie's Composition:

Copper sulfate, g./1 30 l15 29 29 5 Sodium carbonate, g. 30 2 10 25 Potassium sodium tartr 100 30 140 140 25 Sodium hydroxide, g./l 50 20 40 40 7 Foi-malin 37% solution, m1./1. 30 10o 166 166 10 Versene T, g./l.*.-. 17 pH 11.5 11.5 11.5 Temperature C.) 24 24 21 21 l Copper nitrate. 2 Sodium bicarbonate. Mixture of EDTA and triethylamine at equal mol.

(10) Narcuss bath: Furthermore, the present invention can be utilized for A solution: G./l. producing a base plate for thermoprinting and thermo- Copper sulfate 60 copying, if the metal images are produced on the surface Nickel sulfate 16 of a plastic which is a thermal nonconductor. Hydraziue sulfate 45 As described above, the present invention has many B solution: industrial uses and many advantages. The metal images Sodium hydroxide 45 20 produced are very sharp and have a high electric cOn- Potassium sodium tartrate 180 ductivity and a good thermal conductivity. Sodium carbonate 15 The present invention will be explained in more detail by the following examples: (All thickness in the Exam- Mixing A and B solution before using. ples are dry thickness.)

C. GOLD ELE'CTROLESS PLATING llATH 2 2,, EXAMPLE 1 slsguoclglglde "zl': 75 A cellulose triacetate film 135,2 thick' was dipped in a Sodium Citrate "g /1' 50 1N aqueous solution of sodium hydroxide at 50 C. for Sodium h o hs'l''t "g'" 10 15 minutes, by which the surface Was saponiiied to pro- H (b Ny-IHf 7 to 7 5 30 duce a hydrophilic surface part. 'Ihe iilm was then dipped .gem attire "T" 92 to 9'5 in a 0.1 mol aqueous solution of sodium sulfide at 25 C. p for 15 minutes. After removing the solution on the sur- Sec also: nickel electroless plating bath: face by squeezing, the film was dipped in a 0.1 mol aque- (A) ous solution of nickel chloride at C. for 3 minutes,

followed by washing and drying. By these treatments, a

(l) US. Pat. 2,940,018: composition of A. IV (1) (2) U.S. Pat. 2,942,990: composition of A. II (l) (3) M. Schwartz, Proceeding American Electroplaters' Society, 47, 176 (1960): composition of A. IV. (2) (4) E. B. Sanhestre, Metal Finishing, 50 [6]67 (1962):

composition of A. IV (3).

(B) Copper electroless plating bath:

(1) W. Godie, Platingf 51, 1069 (1964): composition of B.(9). (2) Mccornell (U.S. Pat. 2,874,072): composition of Gold electroless plating bath:

(1) S. D. Swan and E. L. Gostin, Metal Finishing, 59, 4 (1961): composition of C.

The metal images produced by the present invention have many advantages. These advantages are as follows: (1) a high electric conductivity and a good thermal conductivity in the metal image area; (2) a high electric resistivity in the non-metal image area (background); (3) rapidness, that is, exposure is rapidly practiced and subsequent treatments are easily carried out; and (4) the metal image area is not injured and a circuit consisting of a narrow metal image area is not easily broken.

The present invention is useful for producing an electric circuit plate and can be used for the correction of circuit designs on circuit plates.

Further, the present invention can be utilized for producing a base plate of printing if the metal images are produced on a preferred hydrophilic surface. Hydrophilic surface used as follows:

(1) The surface of cellulose triacetate or cellulose diacetate is saponied to become hydrophilic.

(2) The surface of polystyrene is processed with chromic acid or corona discharge to make it hydrophilic.

(3) The surface of polyethylene terephthalate is processed with chromic acid to make hydrophilic.

sheet which contained nickel sulfide in a hydrophilic surface part as the diffusion transfer nucleus material was obtained. To this sheet, a silver chlorobromide emulsion (70% silver chloride) containing 1 mol of silver per kg. of the emulsion was applied so as to provide a 3u thickness. The film was exposed to light through a positive original and then developed using a developer having the following composition at 25 C. for 30 seconds.

Water to make 1 litre.

The element was then dipped in warm water at 40 C. to remove the emulsion layer. At this stage, a positive image of the original formed on the element. The element was dipped in a 15% aqueous formalin solution for 8 minutes at 25 C. and then in a 0.8% aqueous palladium chloride solution having a pH of 2.0 for 60 seconds at 50 C. The element was then dipped in a Cahills copper electroless plating at 24 C. for one minute, by which beautiful plating of copper was formed according to the pattern of the original. The electric conductiivty was below 0.2 Q/square. Q/square had a value of 1,400 of the resistivity (Q) of a resistance Wire which had the length of times the width thereof.

EXAMPLE 2 A cellulose triacetate iilm 135,4 thick was dipped in a solution having the following composition at 20 C. for 3 minutes. i

Sodium hydroxide g Ethyl alcohol m1 500 Water ml 500 ous solution of silver nitrate at 25 C. for 3 minutes, followed by washing and drying. By these treatments, a sheet which contained silver sulfide nuclei in a hydrophilic surface part was obtained.

To this sheet, a silver chlorobromide emulsion containing 1.2 mols of silver per kg. of the emulsion was applied to provide a 4p. thickness. The sheet was exposed to reiiection rays using an original having a positive pattern of a circuit by means of a process camera at 16 of iris, 8 seconds, (diaphragm f:16, exposure time 8 seconds) and developed using a developer having the following composition at 20 C. for 20 seconds.

Water to make l litre.

Upon removing the emulsion layer by spraying a jet of warm water at 40 C. thereon, a silver image was produced according to the positive original.

The resulting electric circuit consisting of the positive silver image was dipped into an aqueous solution of palladium chloride having an adjusted pH of 1.5 (palladium chloride content: 3.5%) at 30 C. for 40 seconds and then into a copper electroless solution (commercial name: Top Metalate Bath, produced by Okuno Seiyaku Co.) at for 3 minutes to plate the silver image with copper. The electric conductivity of the circuit obtained by this process was below 0.1 Q/square.

EXAMPLE 3 A sheet element having a 3-layer sandwiched structure was prepared by laminating a polyethylene of g./m.2 in weight with paper having a 100 g./m.2 weight, and laminating the resulting paper with a cellulose acetate butyrate film p thick (161-40, produced by Eastman Kodak Co.). This sheet element was dipped into a solution (prepared by dissolving 50 g. of sodium hydroxide in 500 ml. of methyl alcohol) at 35 C. for 2 minutes to saponify the surface of the cellulose.

The sheet element having a hydrophilic surface was dipped at 25 C. for 2 minutes into a solution prepared by dissolving 10 g. of silver nitrate in 500 ml. of water, adding 500 ml. of a 0.5 N sodium hydroxide solution thereto, and adding an aqueous ammonium solution till the produced silver oxide precipitate dissolved. Then the sheet element was dipped in a 3.7% aqueous formalin solution at 25 C. for 30 seconds, followed by squeezing and drying. By these treatments, a sheet element which contained colloidal silver in the part near the surface of the hydrophilic surface part was produced, the colloidal silver serving as the diffusion transfer nucleus material.

This sheet element was exposed to light through a positive original and developed by a developer having the composition of Example 1 at 25 C. for 30 seconds. By removing the emulsion layer by dipping in warm water at 50 C., silver images were produced according to the positive original. These were intensified with copper images by the electroless plating treatment of Example 1. The thus produced sheet element, in which the images were oleophilic and the surface part of the cellulose was hydrophilic, could be used as a lithographie offset printing plate. Using an available wetting solution and inks, more than 10,000 copies of printed material of good quality were obtained.

EXAMPLE 4 A polyethylene terephthalate film g thick was treated by passage through a fiame jet produced from propane gas and air so as to have a hydrophilic surface. [passing PET film base in the dame of propane gas and air running at 70 m./min., the surface is made oxidated and hydrophilic]. This film was dipped in a 0.2 mol aqueous solution of sodium sulfide at 40 C. for 10 minutes and then the solution on the surface was removed by squeezing. The film was then dipped in a 0.1 mol aqueous solution of nickel chloride at 25 C. for 3 minutes, followed by washing and drying. By these treatments, a polyethylene terephthalate film containing nickel sulfide as diffusion transfer nuclei was produced. To this sheet element, a silver bromoiodide emulsion containing 1.3 mols of silver per kg. of the emulsion (1.5% silver iodide) was applied to provide a 3p thickness. The sheet element was exposed to light through a positive original and developed using a developer having the following composition at 25 C. for 45 seconds.

Water to make 1 litre.

The emulsion layer was removed by dipping in warm water at 45 C.

The element was then dipped into an aqueous formalin solution (25%) at 25 C. for 5 minutes, into a 3% aqueous solution of palladium chloride at 45 C. for 20 seconds and then into a copper electroless solution at 20 C. for 3 minutes to intensify the images with copper.

On the pattern of copper images formed on the sheets, a thermosensitive copying paper was laid. By uniformly applying infrared rays of an intensive luminous flux at the side of the polyethylene terephthalate film free of copper, a duplicated pattern was formed on the thermosensiti've copying paper according to the metal images. -Infrared ray was applied to the side free of copper. The infrared ray is absorbed in black image of silver and transmitted copper.

The copper electroless solution in Example 4 is as follows:

Copper sulfate 5 water --g./l 29 Sodium carbonate ....g./l 25 Potassium sodium tartrate g./l-

Sodium hydroxide g./l 40 Formation 37% solution ml./l.... 166

EXAMPLE 5 To a polyethylene terephthalate film support (thickness 135p), a solution which contained 48 parts vinyl chloride (70 mol percent)vinyl acetate (30 mol percent) copolymer and (polymerization degree is 400) 2.65 parts by weight of titanium dioxide pigment (based on parts by weight of the vinyl chloride-vinyl acetate copolymer) was applied so as to provide a 0.2 g./decimeter2 thickness. A solution of this pigment in 52 parts methylethylketone was applied to the polyester support and dryed at F. for 5 minutes. A composition containing finelydivided colloidal silica and colloidal silver having the following composition was applied to the resulting layer so as to provide a 1pl thickness.

Aqueous dispersion of colloidal silica having 30% by weight solids content 800 Secondary sulfate anionic surface active agent 4 Aqueous solution of colloidal silver 10% by weight) dispersed in casein (20%) 30 A silver chlorobromide photographic emulsion (silver chloride: 70%) was applied to the resulting silica layer.

This photographic image forming base plate was exposed by reflection rays to a positive original by means of a plate making camera at 16 of iris for 6 seconds. The plate was treated with using the same diffusion transfer developer as in Example 1 at 25 C. for 30 seconds.

13 Then the photographic emulsion layer was removed by warm water at 45 C. The silver images were intensified with metal images by electroless plating as described in Example 1. The metal images obtained had an excellent electrical conductivity which was below 1.5 tl/ square.

This invention is used to manufacture printed circuits, oiset printing plates, master plates of heat-printing, master plates of heat duplicating, name plates, etc.

What is claimed is:

1. A process for producing metal images comprising image-exposing, through an original image, a photosensitive element which comprises a photosensitive silver halide photographic emulsion laid on a hydrophilic surface of a plastic which has a surface containing a diffusion transfer nucleus material, forming reversal silver images of the original on the surface of said plastic by a diiusion transfer developing process, removing said emulsion, activating said silver images with a solution of a metal salt, and intensifying said silver images by electrolessly plating a metal thereon.

2. A process for producing metal image as claimed in claim 1 wherein said metal image is nickel, copper, chrome, cobalt, silver or gold image.

3. A process for producing metal image as claimed in claim 1 wherein said silver halide is silver chloride, silver bromide, silver iodide, silver chlorobromide, silver bromoiodide, silver iodochloride, or silver chlorobromoiodide.

4. A process for producing metal image as claimed in claim 1 wherein said plastic is polyethylene terephthalate, polyvinylalcohol, cellulose triacetate, cellulose diacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate or cellulose acetate butyrate.

5. A process for producing metal images as claimed in claim 1 wherein said solution of metal salt is an aqueous solution of noble metal compound.

6. A process for producing metal images as claimed in claim 5 wherein said noble metal compound is selected 14 from palladium (H) chloride, hydrogen gold (IV) chloride or diamine silver nitrate.

7. A process for producing metal images as claimed in claim 6 wherein said noble metal compound is palladium (II) chloride.

8. A process for producing metal images as claimed in claim 2 wherein said metal image is copper.

9. A process for producing metal images as claimed in claim 1, wherein said plastic is a cellulose organic acid ester.

10. A process for producing metal images as claimed in claim 1 wherein said plastic is polyethylene-terephthalate.

11. A process for producing metal images as claimed in claim 1, wherein said plastic is polyethylene.

12. A process for producing metal images as claimed in claim 9, wherein saidhydrophilic surface is obtained by contacting said cellulose organic acid ester with an aqueous solution of an alkali, a mixture of alkalicon taining water and a solvent or an alkali-containing solvent.

13. A process for producing metal images as claimed in claim 10, wherein said hydrophilic surface is obtained by a ilame treatment.

References Cited UNITED STATES PATENTS 3,582,328 6/1971 De Haes et al. 96-29 3,223,525 12/1965 Jonker et al. 96-48 PD 3,645,736 2/1972 MoWat 96-48 PD 3,647,440 3/ 1972 Rasch 96-76 R 3,730,721 5/1973 Williams et al 96-48 PD 3,674,489 7/1972 Wyman 96--48 PD RONALD H. SMITH, Primary Examiner I. L. GOODROW, Assistant Examiner U.S. Cl. X.R.

96-60 R, 48 PD, 29 L, 36.2, 33 

